Improvement in parallel rulers



J. D. HALL.

PARALLEL RULE-R No.1.70,Z.57. Patented Nov.23,1875.

JOHN D. HALL, OF NEW YORK, N. Y.,

PATENT. OFFICE.

ASSIGNOR TO HINMAN L. HALL, OF-

PHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN PARALLEL RULERS.

Specification forming part of Letters Patent No. 170,257, dated November 23, 1875; application filed March 13, 1875.

To an whom it may concern Be it known that I, JoHN D. HALL, of the city, county, and State of New York, have invented a new and useful Improvement in Parallel Rules; and I do hereby declare the slipping on the surface of the material on' which it is placed to be used.

The improved rule will be readily understood by reference to the accompanying drawings, of which- Figure I is a general plan, showing the two sides or bars forming the rule, the adjustable connections between them, and the improved hinge. Fig. II is a detached transverse sectional elevation of one of the pivoted spring-latches by which the parallel connecting-rods are attached to the stationary bar. Fig. III is a longitudinal sectional elevation of one of the side pieces or bars, showing the friction-strip secured to its bottom.

The two side pieces or bars A B are not unlike the similar parts of ordinary parallel rules, and either one or both of them may be graduated with measurements, as desired. The outside or movable piece B may or may not be longer than the stationary piece A, if required. The two parallel connecting-rods O O are secured to the movable piece B by the pivot-pins or screws 0, and to the stationary piece A by the pivoted spring-latches D. These two spring-latch'pieces are attached to the piece A by the pivot-pins or screws 61, on which they turn as on a journal. The spring-latches D are shown in detail in the transverse section in Fig. II, in which is shown the free end 01 of the piece,

. which forms a spring that forces the rod 0 placed in the edges of each of the rods at regular intervals-say, one-half an inch, more or less--and it may, and probably will, be desirable to have each of them marked in plain figures, so as to indicate the distance the piece B shall have been moved out from its original position by the side of and contiguous to the face of the piece A. As it. is desirable to place these parallel rules, when in use, on smooth surfaces, as on a draftsmans paper, or on ladies patterns, or in any similar place where they would be liable to slip and move, therefore I secure. to the bottoms of the pieces A B strips or, which are made of india-rubber, cloth, or other textile fabric, and which pieces are to be secured by means of glue or other suitable appliance to the pieces A B, and wholly prevent slipping of the rule while in use. of wood or metal. -In moving out the piece B to any desired position, press the rod 0 0 back toward its spring at until its notch is released from the pin d, when it can be moved out to any other required notch, when the spring cl will throw rod 0 0 back toward the pin d, so as to hold it on another notch at the exact distance required. A pin, E, which is set in the moving piece B, will'strike therod (J when it is thrown around perpendicular to the piece A, and. will so form a stop to indicate when the pieces A B are thrown apart to their fullest extent, and will also'serve to hold the piece B firmly to work against, as in drawing or cutting with it, for a guide for the instrument.

Inorder to make my parallel rules more portable, and at the same time enable the operator to extend the rules, I have provided the same with joints of a peculiar construe.

tion, which will hold the rules, when extended, in straight lines. These joints are formed by making vertical incisions, P, in the ends R S to be joined, and insert metallic strips T in the same, which are pivoted, atU, to, or near to, the ends. The ends are rounded at V underneath, to allow them to pass each other when being folded.

W and X are metallic strips fastened to the The pieces A B may be made top of R and 8,111 order to keep the rules, when extended in a straight line.

Having thus deseribedmy invention, I de- Sire to claim-- The pieces A B of a parallel rule, conneeted together by the parallel rods O 0', having notches 1c in their edges fo indicate and fix the exact distance the edge of therule B is:

set out from the rule A, the said rods G C beingpiv'oted toathe rule B by the pin 0, and

to'the rule-piece A by the spring-latch Ddd,

as described and set forth.

JOHN D. HALL. Witnesses:

ANTON O". GRONDAL, FRANKLINaBARRITT. 

